Deep brain stimulation (DBS) and other related procedures involving implantation of electrical stimulation leads within the brain of a patient are increasingly used to treat disorders, such as Parkinson's disease, dystonia, essential tremor, seizure disorders, obesity, depression, restoration of motor control, and other debilitating diseases via electrical stimulation via stimulation of one or more target sites, including the ventrolateral thalamus, internal segment of globus pallidus, substantia nigra pars reticulate, subthalamic nucleus (STN), or external segment of globus pallidus. DBS has become a prominent treatment option for many disorders, because it is a safe, reversible alternative to lesioning. For example, DBS is the most frequently performed surgical procedure for the treatment of advanced Parkinson's Disease. There have been approximately 30,000 patients world-wide that have undergone DBS surgery. Consequently, there is a large population of patients who will benefit from advances in DBS treatment options.
During DBS procedures, at least one burr hole is meticulously cut through the patient's cranium so as not to damage the brain tissue below, a large stereotactic targeting apparatus is mounted to the patient's cranium, and a cannula is scrupulously positioned towards the target site in the brain. A stimulation lead is then introduced through the cannula, through the burr hole, and into the parenchyma of the brain, such that one or more electrodes located on the stimulation lead are strategically placed at a target site in the brain of the patient. Once the stimulation lead is properly positioned, the portion of the stimulation lead exiting the burr hole is subcutaneously routed underneath the patient's scalp to an implantable pulse generator (IPG) implanted in the patient at a site remote from the burr hole (e.g., the patient's shoulder or chest region). Further details discussing the treatment of diseases using DBS are disclosed in U.S. Pat. Nos. 6,845,267, 6,845,267, and 6,950,707, which are expressly incorporated herein by reference.
Significantly, it is crucial that proper location and maintenance of the stimulation lead position be accomplished in order to continuously achieve efficacious therapy. This is especially so with DBS applications, in which cases, the target site (or sites) that is intended for electrical stimulation is about the size of a pea and is located deep within the patient's brain. Thus, lead displacements of less than a millimeter may have a deleterious effect on the patient's therapy. Therefore, it is important that that the electrode(s) of the stimulation lead be accurately located at the target site and that such electrode(s) be securely maintained at the target site during and after implantation of the stimulation lead. In addition, it is important that the burr hole be sealed around the stimulation lead to prevent infection or leakage of cerebrospinal fluid.
To address these issues, and with reference to FIGS. 1-3, a cranial burr hole plug 1, may be installed within the burr hole 2 during the implantation procedure to hold the stimulation lead 3 in place, thereby maintaining the relevant electrode(s) of the stimulation lead 3 at the target site within the brain 4 of the patient, as well as to seal the burr hole 2. As further shown in FIG. 2, the burr hole plug 1 may comprise a multitude of components, including a ring-shaped plug base 5, which is permanently mounted to the patient's cranium 8 using fasteners, such as screws 9, a retainer 6, which is mounted within the plug base 5 and is used to secure the lead 3 in place, and a cap 7, which can be installed onto the plug base 5 over the retainer 6 to permanently secure the stimulation lead 3, as well as to seal the burr hole 2. Further details regarding these types of burr hole plugs are disclosed in U.S. patent application Ser. No. 12/258,382, entitled “Burr Hole Plug With Self-Centering Tabs,” which is expressly incorporated herein by reference.
Notably, any displacement of the portion of the stimulation lead 3 exiting the burr hole 2 will result in the translation of the electrodes positioned in the brain 4 relative to the target site, thereby requiring the stimulation lead 3 to be repositioned—a time-consuming process. Although the retainer 6 is designed to temporarily secure the stimulation lead 3 before the cap 7 is installed onto the plug base 5, the distal tip of the stimulation lead 3 may be prone to movement when the proximal end of the stimulation lead 3 is flexed, as shown in FIG. 3.
There, thus, remains a need to better secure a stimulation lead within a burr hole plug to prevent or minimize migration of the distal tip of the stimulation lead relative to the target site in the brain.